1. Field of the Invention
The present invention relates generally to film cassettes. More specifically, the present invention relates to autoradiography and chemiluminescence cassettes.
2. Related Art
In the science of autoradiography, a specimen sheet holding a radiation emitting material (e.g., a radioactive material or a light-emitting material) along with a radiation-sensitive film are inserted into an autoradiography cassette. The autoradiography cassette, which is light tight when loaded with the film and specimen, facilitates storage and handling of the film during the required exposure period.
A specimen sheet may include the end product of electrophoresis gel separation of cell tissues. Such gels are generally transferred to a membrane and dried. The transferred products of such a separation are treated with elements which have an affinity for the specimen. Examples of such elements include radioactively tagged antibodies when the specimen is a protein, and a tagged DNA probe when the specimen is DNA.
The radiation level of the specimens is generally low. However, a photographic image may be obtained in an autoradiography cassette because of the close proximity of the membrane and film. In addition, intensifying screens can be used to improve autoradiographic detection. Generally, when using low level radioactive specimens the autoradiography cassette is placed in an extremely cold environment, e.g., -70 degrees Celsius, to allow for proper film exposure.
Conventional autoradiography cassettes are often large and cumbersome to use. They are generally made of heavy steel or aluminum and have thicknesses that exceed 0.5 inches. When inserting a film and a radiation emitting specimen, one conventional cassette requires that a cover be forced against a base using two or more locking bars. Closing such a cassette can be difficult, especially in a dark room.
Another type of autoradiography cassette is made of a cardboard exterior with a paper envelope inside. While easier to use, these cassettes do not ensure a quality contact between a sample (e.g., a radioactive specimen) and the film. Furthermore, the cardboard cassettes must be frequently replaced because, with use, the light tight seals break and the cardboard warps, reducing the quality, of contact between the sample and the film.
What is needed is a durable, reliable and easy-to-use autoradiography cassette.